Stridor: Causes And Differential Diagnosis

Stridor is noisy respiration produced by turbulent air flow
through the narrowed air passages. It may be heard during
inspiration, expiration or both.
• Inspiratory stridor is often produced in obstructive
lesions of supraglottis or pharynx, e.g. laryngomabci8
or retropharyngeal abscess.
• Expiratory stridor is produced in les ions of thoracic
trachea, primary and secondary bronchi, e.g.
bronchial foreign body, tracheal stenosis.
• Biphasic stridor is seen in lesions of glottis, subglottis
and cervical trachea, e.g. laryngeal papillomas,
vocal cord paralysis and subglottis stenosis.
Aetiology:
Stridor may arise from lesions of nose , tongue, mandible,
pharynx, larynx or trachea and bronchi. Common causes
of stridor in infants and children are given below:

(a) Nose. Choanal atresia in newborn.

(b) Tongue. Macroglossia due to cretinism, haemangioma
or lymphangioma, dermoid at base of tongue,
lingual thyroid.
(c) Mandible. Micrognathia, Pierre-Robin syndrome. In
these cases, stridor is due to falling back of tongue.
(d) Pharynx. Congenital dermoid, adenotonsillar hypertrophy,
retropharyngeal abscess, tumours.
( e ) Larynx: (i) Congenital: Laryngeal web, laryngomalacia,
cysts, vocal cord paralysis, subglottic stenosis.
(ii) Inflammatory: Epiglottitis, laryngotracheitis,
diphtheria, tuberculosis.
(iii) Neoplastic: Haemangioma and juvenile multiple
papillomas. carcinoma in adults.
(iv) Traumatic: Injuries of larynx, foreign bodies,
oedema following endoscopy. or prolonged
intubation.
(v) Neurogenic: Laryngeal paralysis due to acquired
lesions.
(vi) Miscellaneous: Tetanus, tetany, laryngismus
stridulus.
( f) Trachea and bronchi
(i) Congenital: Atresia, stenosis, tracheomalacia.
(ii) Inflammatory: Tracheobronchitis.
(iii) Neoplastic: Tumours of trachea.
(iv) Traumatic: Foreign body, stenosis trachea
(e.g. following prolonged intubation or tracheostomy).
(g) Lesions outside respiratory tract
(i) Congenital: Vascular rings (cause stridor and
dysphagia). oesophageal atresia, tracheooesophageal
fistula, congenital goitre, cystic
hygroma.
(ii) Inflammatory: Retropharyngeal and retrooesophageal
abscess .
(iii) Traumatic: Foreign body oesophagus (secondary tracheal
compression) .
(iv ) Tumours: Masses in neck.

Management:

History
Stridor i, a physical sign and not a disease. Attempt should
always be made to discover the cause. It is important to
elicit:
(a) Time of onset to find whether cause is congenital or
acquired.

(b) Mode of onset. Sudden onset (foreign body, oedema),
grad ual and progressive (laryngomalacia. subglott ic
haemangioma, juvenile papillomas).
(c) Duration. Short (foreign body, oedema, infections),
long (laryngomalacia, laryngeal stenosis, subglottic
haemangioma, anomalies of tongue and Jaw).
(d) Relation to feeding. Aspiration in laryngeal paralysis,
oesophageal atresia, laryngeal cleft, vascular ring,
foreign body oesophagus.
(e) Cyanotic spells. Indicate need for airway maintenance.
(f) Aspiration 0r ingestion of a foreign body.
(g) Laryngeal trauma. Blunt injuries to larynx, intubation,
endoscopy.
Physical Examination
(a) Stridor is always associated with respiratory distress.
There may be recession in suprasternal notch, sternum,
intercostal spaces and epigastrium during
inspiratory efforts.
(b) Note whether stridor is inspiratory, expiratory or
biphasic which indicates the probable site of
obstruction.
(c) Note associated characteristics of stridor.
(i) Snoring or snorting sound-nose or nasopharyngeal
cause.
(ii) Gurgling sound and muffled voice-pharyngeal
cause.
(iii) Hoarse cry or voice- laryngeal cause at vocal
cords. Cry is normal in laryngomalacia and
subglottic stenosis.
(iv) Expiratory wheeze-bronchial obstruction.
(d) Associated fever indicates infective condition,
e.g. acute laryngitis, epiglottitis, laryngo-tracheobronchitis
or diphtheria.
(e) Stridor of laryngomalacia, micrognathia, macroglossia
and innominate artery compress ion disappears
when baby lies in prone position.
(f) Sequential auscultation with unaided ear and with
stethoscope over the nose, open mouth, neck and
the chest helps to localise the probable site of origin
of stridor.
(g) Examination of nose, tongue, jaw and pharynx and
larynx can exc lude local pathology in these areas. In
adults, indirect laryngoscopy can be done easily while
infants and children require direct laryngoscopy.
Radiography
(a) X-ray of chest and soft tissue neck both in anteroposterior
and lateral views.
(b) Fluoroscopy to see chest movements both during
inspiration and expiration.
(c) Tomography of chest for mediastinal mass.
(d) Oesophagogram with lipoidal for atresia of oesophagus,
tracheobronchial fistula or aberrant vessels.
(e) Angiography, if aberrant vessels are suspected.
(f) Xeroradiography is useful to show soft tissue lesions
in the neck.
(g) CT scan.
Direct Laryngoscopy Without Anaesthesia
A quick direct laryngoscopy can be done in infants and
small children without anaesthesia. Howeve r, resuscitative
measures and tracheostomy tray should be made avai lable.
Direct laryngoscopy also gives opportunity to see if intubation
will be possible or tracheostomy will be requ ired
for further examination.
General Anaesthesia Followed by
Bronchoscopy, Laryngoscopy and
Oesophagoscopy
After slow induction, bronchoscopy is done first. It is
useful to find any obstruction in air passage from subglottis
to bronch i, removal of the obstruction, obtain aspirate
or biopsy. If 3.5 mm size bronchoscope can be passed,
intubation of the child is possible. After bronchoscopy,
child is intubated and detailed examination of the larynx
and oesophagus can then be done. Larynx should again
be examined when patient is coming ou t of anaesthesia
and the tube has been removed to see active movements
of vocal cords to exclude laryngeal paralysis.
Treatment
Once the diagnosis has been made, treatment of exact
cause can be planned.